A distributed antenna system (“DAS”) can include one or more head-end units and multiple remote units coupled to each head-end unit. A DAS can be used to extend wireless coverage in an area. Head-end units can be coupled to one or more base stations. A head-end unit can receive downlink signals from the base station and distribute downlink signals in analog or digital format to one or more remote units. The remote units can transmit the downlink signals to user equipment devices within coverage areas serviced by the remote units. In the uplink direction, signals from user equipment devices may be received by the remote units. The remote units can transmit the uplink signals received from user equipment devices to the head-end unit. The head-end unit can transmit uplink signals to the serving base stations. Often, strong signals at the downlink path can interfere with incoming signals at the uplink path. It may be desirable to minimize the interference between downlink and uplink paths in a DAS.
Remote units can operate in a network that radiates frequency-division duplexing (“FDD”) signals. In an FDD network, remote units and repeaters can use transmit/receive duplexers or filter stages to protect received signals in a receiving communications path from interference caused by signals other than the received signals. But, duplexers and filters do not allow for frequency agnostic, radio frequency front-ends unless significant limitations are introduced through transmit and receive antenna isolation.